The present invention relates to an information output system and more particularly relates to an information output system having a character display unit or a printer as its information output unit.
As a general unit for yielding visible outputs of characters formed by dot patterns, a terminal unit comprising a character display unit such as a CRT display and a printer such as a line printer, ink jet printer, or a wire matrix type printer is known. Such a terminal unit may be used as an off-line output unit. In general, however, a system wherein such a terminal unit is connected to a host, such as a central processing unit or a terminal control unit, to form a terminal system and the data edited by the host is outputted to a character display or a printer of the terminal unit in an on-line approach is well known.
In such a known information output system, a CRT display which is able to display 80 characters per line is the most widely used as the character display unit and a serial printer of the wire dot matrix type which is able to print 132 characters per line (hereafter simply referred to as "printer") is the most widely used. When the contents of a picture on the CRT display composed of 80 characters by 24 lines, for example, are to be outputted on the printer as a hard copy in the off-line approach, the 80 characters by 24 lines are printed as they are. On the other hand, a printer is also known which is able to print 132 characters per line under control of a control circuit by receiving the data which has been edited in the form of 132 characters per line beforehand in the host and transferred to the serial printer.
Recently, various kinds of paper and slips are loaded on a printer and in many cases it is desired to arbitrarily change the output format on the printer. For instance, it may be desired to print the data in the form of 132 characters per line whereas the data is displayed in the form of 80 characters per line on the CRT display.
In the conventional information output system, the above described requirement is satisfied by providing an application program in the host. The application program is composed of the picture design of the CRT display for displaying 80 characters per line, printer output design for printing 132 characters per line, and a program for converting the text form of 80 characters per line into the text form of 132 characters per line. When the contents of a displayed picture are to be printed on the printer, the data represented in the 80-character form are successively converted into the 132-character form by this program. The data thus converted is transferred to the printer and printed in the form of 132 characters per line under the control by a control character.
However, such an approach has drawbacks in that the application program in the host has an increased number of steps and is complicated and that it takes a relatively long time to convert the output data.
As a solution to prevent the above described drawbacks, the following approach which is not known can be conceived. That is to say, a CRT display which is able to display the data in the form of 132 characters per line and a printer which is able to effect hard copy printing in the form of 132 characters per line are acditionally connected to the above described output system. According to the print format of the paper loaded on the printer, let us consider for example a method wherein the operator specifies each time through the keyboard or the like either a CRT display of the 80-character form or the CRT display of the 132-character form.
However, preparation of fixed-form CRT displays and printers according to the demanded display format and print format each time brings about an uneconomical and inflexible system. In addition, it is very troublesome for the operator to specify each time a printer and a CRT display for exclusive use according to the required display format or print format. Further, the operator may commit an error in specification. For instance, if a printer of 132 characters per line is specified as a printer for hard copy through a mistake whereas the picture on the CRT display comprises 80 characters per line, the print data becomes confused and illegible.